1. Field of the Invention
The present invention relates to a water aeration apparatus, more particularly to an aeration apparatus which takes advantage of the raising flotation or suction action of air under pressure for causing a large amount of water to be exposed to that action for aeration purposes or water purification as well as anti-freezing purposes in water-filled areas such as dams, impounded water or reservoirs, and lakes and marshes.
2. Description of the Prior Art
A conventional water aeration apparatus of the type using the raising or suction action of air supplied under pressure to the water has been used for aeration purposes in dams impounded water reservoir installations or natural water resources such as lakes and marshes, and is known to provide an effective means for that purposes (as disclosed in the Japanese Utility Model Official Publication as opened to the public examination under No. 57 (1982)-39117).
The conventional apparatus includes a tubular casing, which has a single passage through which water is pumped upwardly by its exposure to the action of air supplied under pressure, and the passage has a bore diameter range of 40 cm to 50 cm. Because of the single water passage construction, the single tubular casing has limitations in its capacity for handling water at a time. When this apparatus is used in a dam installation or elsewhere which contains water to a depth of for example 20 m or more, each tubular casing is required to be installed for one million volumetric tons of water to be handled. Therefore, it is necessary to increase the number of the individual tubular casing installations as the volume of water to be handled increases.
It should readily be understood from the above that for a single passage tubular casing, ten tubular casing installations are required for handling ten million volumetric tons of water, and one hundred installations are required for one hundred million tons of water, which can easily be found from a simple calculation. A corresponding number of additional installations are required for additional tons of water. Increasing the number of individual tubular casing installations results in additional pieces of accompanying equipment such as air supply hoses, air compressors, and motors, in addition to which require regular or occasional maintenance service. This raises a problem to be solved. As one solution, it may be suggested that the number of individual tubular casing installations be reduced by increasing the transverse cross section or bore diameter of a single tubular casing. Increasing the diameter, however, leads to a considerable increase in the volumetric capacity of an air chamber which is located below the tubular casing. The volume of such air chamber may be found from the following equation, for example: EQU V=k(4/3).pi.r.sup.3
where k is a factor of 0.3 to 1.0, r is a raduis of a tubular casing, and V is the volume of an air chamber.
It can be seen from the above equation that the volume of the air chamber increases in proportion to the cube of the radius of the tubular casing. Thus, increasing the diameter for the tubular casing poses a problem since it requires a larger air supply. This is undesirable from the energy saving needs.